Microplastics in sea surface waters around Scotland

Seabirds as biovectors in the transport of plastic debris across ecosystem borders: A case study from the Humboldt Current Upwelling System

Seabirds have become biovectors of plastic pollutants between marine and terrestrial ecosystems, and transport of plastics to their nesting sites becomes relevant due to increasing levels of pollution. To determine the pathways by which plastic reaches their colonies, we analysed the abundance of plastics at the nesting sites of five seabird species (Humboldt penguin Spheniscus humboldti, Peruvian booby Sula variegata, kelp gull Larus dominicanus, grey gull Leucophaeus modestus, Markham's storm-petrel Hydrobates markhami) nesting in northern Chile. Seabirds were primarily grouped according to their nesting behaviour, but two species foraging in contrasting habitats (kelp gull and Markham's storm-petrel) were also compared directly. The abundance, type, and polymer of macro-, meso- and microplastics were analysed in the soil of colonies and control sites, and microplastic ingestion was evaluated for selected species. Densities of plastics in colonies of surface-nesting seabirds ranged from 0 to 21.4 items m-2 (mainly plastic bags and thin films), and 0.002 to 19.7 items m-2 (mainly hard fragments) in colonies of burrow-nesting seabirds. Mean microplastic loads in the stomachs of seabirds were between 3.7 ± 4.2 plastic items individual-1. Overall, the abundances of plastic items in all seabird colonies were low, suggesting a limited transfer of plastics from sea to land. For kelp gulls, the results indicate transfer of macroplastic items to colonies, reaching the colony via regurgitates, with landfills considered as the main plastic source. Our results suggest that contrasting nesting behaviour and foraging habitats among species can explain differential plastic accumulation in seabird colonies, but also other factors, such as wind, contribute to the accumulation of plastic debris in colonies. Proper management of sanitary landfills are key to reduce plastic contamination of coastal seabirds and their colonies.

Gut microbiota, a key to understanding the knowledge gaps on micro-nanoplastics-related biological effects and biodegradation

Micro-nanoplastics (MNPs) pollution as a global environmental issue has received increasing interest in recent years. MNPs can enter and accumulate in the organisms including human beings mainly via ingestion and inhalation, and large amounts of foodborne MNPs have been frequently detected in human intestinal tracts and fecal samples. MNPs regulate the structure composition and metabolic functions of gut microbiota, which may cause the imbalance of intestinal ecosystems of the hosts and further mediate the occurrence and development of various diseases. In addition, a growing number of MNPs-degrading strains have been isolated from organismal feces. MNPs-degraders colonize the plastic surfaces and form the biofilms, and the long-chain polymers of MNPs can be biologically depolymerized into short chains. In general, MNPs are gradually degraded into small molecule substances (e.g., N2, CH4, H2O, and CO2) via a series of enzymatic catalyses, mainly including biodeterioration, fragmentation, assimilation, and mineralization. In this review, we outline the current progress of MNPs effects on gut microbiota and MNPs degradation by gut microbiota, which provide a certain theoretical basis for fully understanding the knowledge gaps on MNPs-related biological effect and biodegradation.

Concentrations and carbonyl index of microplastic in surface seawater in southeastern coastal region off Japan, Northwestern Pacific

In this study, microplastic concentrations in the southeastern coastal regions of Japan were measured along the northward ocean current at seven stations from Okinawa to Tokai region. Concentrations ranged from 0.014 to 0.094 pieces/m3, except for a station near the Bungo Channel mouth, which had 0.723 pieces/m3. Polystyrene (PS) foam was most prevalent near the east side of Kyushu, suggesting origination from nearby coastal areas. Fragmentation levels were higher in the Tokai region. In addition, carbonyl index (CI) of polyethylene (PE) microplastics increased northward, indicating northward movement from southern regions. Standard PE microplastics showed chemical treatment does not significantly alter CI values. Further spectral analysis suggested potential oxidation of polypropylene (PP) and PS foam by chemical treatment. This study provides a comprehensive understanding of the abundance, distribution, and characteristics of microplastics in the southeastern coastal regions of Japan in the northwest Pacific, enhancing the understanding of environmental fate of microplastics.

Microplastic abundance in the semi-enclosed Osaka Bay, Japan

Anthropogenic particles in sea surface water of the semi-enclosed Osaka Bay were identified using stereomicroscopy, classified according to polymer type using Fourier-transform infrared spectroscopy (FTIR), and categorized according to their physical characteristics. A total of 565.1 particles were detected in the water samples. However, plastic particles accounted for only 22.4% of the particles. Microplastic abundance in Osaka Bay showed seasonal variance from 8.9 ± 1.4 (in May) to 22.8 ± 6.5 particles/L (in July), which is consistent with previous reports in other semi-enclosed bays. Microplastics were mainly fragmented and fiber shaped, with gray and colorless/white coloration. The dominant polymer types were polypropylene, poly(methylmethacrylate), polyester, polyethylene, and polyethylene terephthalate. Generally, there were considerably higher abundances of microplastics at offshore sites compared with nearshore sites. The results of this study suggest that local river effluents and marine-related activities are probable sources of microplastics in Osaka Bay.

Landscape and risk assessment of microplastic contamination in farmed oysters and seawater along the coastline of China

Microplastic (MP) pollution poses a significant threat to marine ecosystem and seafood safety. However, comprehensive and comparable assessments of MP profiles and their ecological and health in Chinese farming oysters are lacking. This study utilized laser infrared imaging spectrometer (LDIR) to quantify MPs in oysters and its farming seawater at 18 sites along Chinese coastlines. Results revealed a total of 3492 MPs in farmed oysters and seawater, representing 34 MP types, with 20-100 µm MP fragments being the dominant. Polyurethane (PU) emerged as the predominant MP type in oysters, while polysulfones were more commonly detected in seawater. Notably, oysters from the Bohai Sea exhibited a higher abundance of MPs (13.62 ± 2.02 items/g) and estimated daily microplastic intake (EDI, 2.14 ± 0.26 items/g/kg·bw/day), indicating a greater potential health risk in the area. Meanwhile, seawater from the Yellow Sea displayed a higher level (193.0 ± 110.7 items/L), indicating a greater ecological risk in this region. Given the pervasiveness and abundance of PU and its high correlation with other MP types, we proposed PU as a promising indicator for monitoring and assessing the risk MP pollution in mariculture in China. These findings provide valuable insights into the extent and characteristics of MP pollution in farmed oysters and seawater in China.

Hotspots of Floating Plastic Particles across the North Pacific Ocean

The pollution of the marine environment with plastic debris is expected to increase, where ocean currents and winds cause their accumulation in convergence zones like the North Pacific Subtropical Gyre (NPSG). Surface-floating plastic (>330 μm) was collected in the North Pacific Ocean between Vancouver (Canada) and Singapore using a neuston catamaran and identified by Fourier-transform infrared spectroscopy (FT-IR). Baseline concentrations of 41,600-102,700 items km-2 were found, dominated by polyethylene and polypropylene. Higher concentrations (factors 4-10) of plastic items occurred not only in the NPSG (452,800 items km-2) but also in a second area, the Papaha̅naumokua̅kea Marine National Monument (PMNM, 285,200 items km-2). This second maximum was neither reported previously nor predicted by the applied ocean current model. Visual observations of floating debris (>5 cm; 8-2565 items km-2 and 34-4941 items km-2 including smaller "white bits") yielded similar patterns of baseline pollution (34-3265 items km-2) and elevated concentrations of plastic debris in the NPSG (67-4941 items km-2) and the PMNM (295-3748 items km-2). These findings suggest that ocean currents are not the only factor provoking plastic debris accumulation in the ocean. Visual observations may be useful to increase our knowledge of large-scale (micro)plastic pollution in the global oceans.

Capabilities of simultaneous 193 nm - LIBS/LA-ICP-MS imaging for microplastics characterization

Microplastics (MPs) are currently one of the major environmental challenges within our society. With the awareness of the impact of MPs on the environment increasing over the last years, the need for increased monitoring as well as comprehensive analysis to better understand the fate and impact of MPs has become more and more important. A major aspect of MP characterization is the assignment of the polymer type of individual particles. Here, per- and poly-fluoroalkyl substances (PFAS), originating from fluor-containing polymers, have gained a lot of attention due to the severe environmental impact. Additionally, quantitative analysis of the metal content is of great interest in the field, since MPs are prone to either leaching (in)organic additives into the environment or taking up and accumulating hazardous components (e.g., heavy metals). In this work we demonstrate the capabilities of a simultaneous LIBS/LA-ICP-MS setup for the analysis of MPs. In the first part, we demonstrate the potential of targeted LIBS analysis for the imaging of fluor-containing polymers. Using a laser spot size of 5 μm combined with highly sensitive ICCD detection enables analysis of particles in the low μm range. In the second part we combine the polymer-identification capabilities of LIBS with the high sensitivity of ICP-MS to perform matrix-matched quantification of the metal content of individual MPs. In this case we use a spot size of 50 μm facilitating polymer classification with a broadband spectrometer, resulting in detection limits of 0.72 μg/g for Pb and 9.5 μg/g for Sn simultaneously measured using ICP-MS.

Identification and physico-chemical characterization of microplastics in marine aerosols over the northeast Arabian Sea

Microplastics (MPs) in the atmosphere can undergo long-range transport from emission regions to pristine terrestrial and oceanic ecosystems. Due to their inherent toxic and hazardous characteristics, MPs pose serious risks to both human well-being and the equilibrium of ecosystem. The present study outlines the comprehensive characterization, spanning physical and chemical attributes of MPs associated with atmospheric aerosols. Total suspended particulates (TSPs) were collected on a quartz fibre filter by operating a high-volume sampler for 24 h during distinct years (March, 2016 and November, 2020) at a coastal location in the northeast Arabian Sea. Subsequent to the sampling, a series of techniques were applied including density separation. The assessment and scrutiny of the MPs was carried out using stereo-zoom microscopy with supplementary validation using advanced fluorescence microscopy for enhanced precision in identification. Our comparative assessment suggests peroxide treatment followed by density separation could be a robust procedure for the definitive identification and characterization of MPs in the atmosphere. Average total abundance of MPs was found to be 1.30 ± 0.14 n/m3 in 2016 and 1.46 ± 0.12 n/m3 in 2020 with fibres, fragments and films having similar relative contributions (41 %, 31 %, 28 % in 2016 and 40 %, 35 %, 25 % in 2020). Fibres were found to be dominant morphotype followed by fragments and films over the coastal region of the Arabian Sea. In order to unravel the detailed chemical nature of these MPs, spectral analysis using μ-FTIR was carried out. The outcome of the analysis showed prevailing polymers as polyvinyl chloride and polymethyl methacrylate (50545 %) as dominant polymers followed by polyester (15 %), styrene butyl methacrylate (11 %), and polyacetal (9 %). MPs present in the vicinity of the Arabian Sea have potential to supply nutrients and toxicants, consequently can contribute to the modulation of the surface water biogeochemical processes.

Characterization and source apportionment of microplastics in Indian composts

Microplastics (MP), small plastic particles under 5 mm, are pollutants known to carry heavy metals in ecosystems. Composts are a significant source of soil microplastics. This study examined MSW composts from Kochi and Kozhikode in India for microplastic concentrations and heavy metals' accumulation thereon. Microplastics were isolated using zinc chloride density separation, with Fenton's reagent used for organic matter oxidation. Resin types were identified using FTIR analysis that showed the presence of PE, PP, PS, nylon, PET, and allyl alcohol copolymer. In Kozhikode's compost, the average concentration of microplastics was 840 ± 30 items/kg, while Kochi had 1600 ± 111 items/kg, mainly polyethylene films. PE was the most prevalent resin, comprising 58.3% in Kozhikode and 73.37% in Kochi. Heavy metal analysis of MP showed significant concentrations of lead, cadmium, zinc, copper, and manganese adsorbed on the surface of microplastics. The concentrations of heavy metals in the MP before Fenton oxidation ranged from 1.02 to 2.02 times the corresponding concentrations in compost for Kozhikode and 1.23 to 2.85 times for Kochi. Source apportionment studies revealed that 64% of microplastics in Kozhikode and 77% in Kochi originated from single-use plastics. Ecological risk indices, PLI and PHI, showed that composts from both locations fall under hazard level V. The study revealed that compost from unsegregated MSW can act as a significant source of microplastics and heavy metals in the soil environment, with single-use plastics contributing major share of the issue.

Harnessing synthetic biology to enhance ocean health

Ocean health is faltering, its capability for regeneration and renewal being eroded by a steady pulse of anthropomorphic impacts. Plastic waste has infiltrated all ocean biomes, climate change threatens coral reefs with extinction, and eutrophication has unleashed vast algal blooms. In the face of these challenges, synthetic biology approaches may hold untapped solutions to mitigate adverse effects, repair ecosystems, and put us on a path towards sustainable stewardship of our planet. Leveraging synthetic biology tools would enable innovative engineering approaches to augment the natural adaptive capacity of ocean biological systems to cope with the swiftness of human-induced change. Here, we present a framework for developing synthetic biology solutions for the challenges of plastic pollution, coral bleaching, and harmful algal blooms.

Graphene and gold nanoparticle-based bionanocomposite for the voltammetric determination of bisphenol A in (micro)plastics

The monitoring of endocrine disruptors in the environment is one of the main strategies in the investigation of potential risks associated with exposure to these chemicals. Bisphenol A is one of the most prevalent endocrine-disrupting compounds and is prone to leaching out from polycarbonate plastic in both freshwater and marine environments. Additionally, microplastics also can leach out bisphenol A during their fragmentation in the water environment. In the quest for a highly sensitive sensor to determine bisphenol A in different matrices, an innovative bionanocomposite material has been achieved. This material is composed of gold nanoparticles and graphene, and was synthesized using a green approach that utilized guava (Psidium guajava) extract for reduction, stabilization, and dispersion purposes. Transmission electron microscopy images revealed well-spread gold nanoparticles with an average diameter of 31 nm on laminated graphene sheets in the composite material. An electrochemical sensor was developed by depositing the bionanocomposite onto a glassy carbon surface, which displayed remarkable responsiveness towards bisphenol A. Experimental conditions such as the amount of graphene, extract: water ratio of bionanocomposite and pH of the supporting electrolyte were optimized to improve the electrochemical performance. The modified electrode displayed a marked improvement in current responses for the oxidation of bisphenol A as compared to the uncovered glassy carbon electrode. A calibration plot was established for bisphenol A in 0.1 mol L^-1 Britton-Robinson buffer (pH 4.0), and the detection limit was determined to equal to 15.0 nmol L^-1. Recovery data from 92 to 109% were obtained in (micro)plastics samples using the electrochemical sensor and were compared with UV-vis spectrometry, demonstrating its successful application with accurate responses.

Seasonal distribution of microplastics in surface waters of the Northern Indian Ocean

Seven expeditions were carried out during pre-monsoon, monsoon and post monsoon in 2018-2019 for marine plastic collection in surface waters of Northern Indian Ocean. PE and PP (83 %) is the dominant type of polymer found in the surface waters. Colored particles account for 67 % of all particles, with fibre/line accounting for 86 %. The average (Mean ± SD) microplastics concentration in the Northern Indian Ocean during pre-monsoon is 15,200 ± 7999 no./km², Monsoon is 18,223 ± 14,725 no./km² and post monsoon is 72,381 ± 77,692 no./km². BoB during pre-monsoon and post monsoon the microplastic concentration remains same except in the northern BoB this change is caused due to weak winds. Microplastics concentration varied both spatially, temporal and heterogeneity in nature. These differences are caused by effect of wind and seasonal reversal of currents. Microplastics collected in the anticyclonic eddy are 129,000 no./km².

Comparative evaluation of the carbonyl index of microplastics around the Japan coast

The carbonyl index (CI) of polyethylene and polypropylene microplastics (MPs) (2950 particles) collected in coastal waters around Japan was investigated. The CI of MPs was calculated by the specified area under band technique. The mean MP CI in all samples (regardless of shape and color) was 0.69 ± 0.34 and 0.70 ± 0.34 for polyethylene and polypropylene, respectively, and there was no significant difference in the color or shape of the MPs. The polyethylene, white, and fragment MPs CI was negatively (p < 0.05) correlated with the major length of the MPs. Large MPs with relatively little deterioration were distributed along the west coast of the Sea of Japan, whereas small MPs were distributed along the east coast. Our findings of this gradual change in the deterioration of MPs, based on geographical distribution, are in accordance with literature CI-size and MP degradation hypotheses.

Dynamic characteristics of microplastics under tidal influence and potential indirect monitoring methods

Rivers are an important channel for the transport of microplastics from inland areas to the ocean. It is of great significance to explore the dynamic changes in microplastic pollution characteristics under tidal fluctuations to understand the exchange of microplastics between rivers and oceans. In this study, the occurrence of microplastics in typical tidal channels in the lower reaches of the Dong River was investigated during the wet and dry weather seasons, and high frequency continuous dynamic monitoring of microplastics was carried out in a typical tidal cross section during a tidal cycle. The abundances of microplastics during wet and dry weather seasons were 3.97-102.87 ± 28.63 item/m³ and 5.43-56.43 ± 14.32 item/m³, respectively. The microplastics generally exhibited a fluctuating growth pattern, with low contents in the upstream area and high contents in the downstream area, and the abundance of microplastics differed greatly in the different functional zones. The dynamic monitoring results showed that the abundance of microplastics was clearly affected by the tides, in that it increased during the flood tide and decreased during the ebb tide, with abundances ranging from 11.15 to 95.26 item/m³. In addition, there was a significant linear relationship between the abundance of microplastics and flow in the typical tidal cross section. The relationship between the response of microplastic pollution characteristics and tides combined with local hydrometeorological factors may be a potentially effective real-time monitoring method for assessing microplastic pollution indirectly.

Role of mangrove forest in interception of microplastics (MPs): Challenges, progress, and prospects

Mangroves receive microplastics (MPs) from terrestrial, marine and atmospheric sources, acting as a huge filter for environmental MPs between land and sea. Due to the high primary production and complex hydrodynamic conditions in mangroves, MPs are extensively intercepted in various ways while flowing through mangroves, leading to a long-standing but fiercely increasing MPs accumulation. However, current researches mainly focused on the occurrence, source and fate of MPs pollution in mangroves, ignoring the role of mangrove forests in the interception of MPs. Our study firstly demonstrates that mangrove ecosystems have significantly greater MPs interception capacity than their surrounding environments. Then, the current status of studies related to the interception of MPs in mangrove ecosystems is comprehensively reviewed, with the main focus on the interception process and mechanisms. At last, the most pressing shortcomings of current research are highlighted regarding the intercepted flux, interception mechanisms, retention time and ecological risks of MPs in mangrove ecosystems and the relevant future perspectives are provided. This review is expected to emphasize the critical role of mangrove forests in the interception of MPs and provide the foundational knowledge for evaluating the MPs interception effect of mangrove forests globally.

Microplastics in water systems: A review of their impacts on the environment and their potential hazards

Microplastics, the microscopic plastics, are fragments of any type of plastic that are being produced today as plastic waste originating from anthropogenic activities. Such microplastics are discharged into the environment, and they enter back into the human body through different means. The microplastics spread in the environment due to environmental factors and the inherent properties of microplastics, such as density, hydrophobicity, and recalcitrance, and then eventually enter the water environment. In this study, to better understand the behavior of microplastics in the water environment, an extensive literature review was conducted on the occurrence of microplastics in aquatic environments categorized by seawater, wastewater, and freshwater. We summarized the abundance and distribution of microplastics in the water environment and studied the environmental factors affecting them in detail. In addition, focusing on the sampling and pretreatment processes that can limit the analysis results of microplastics, we discussed in depth the sampling methods, density separation, and organic matter digestion methods for each water environment. Finally, the potential hazards posed by the behavior of aging microplastics, such as adsorption of pollutants or ingestion by aquatic organisms, due to exposure to the environment were also investigated.

Microplastics occurrence, detection and removal with emphasis on insect larvae gut microbiota

Microplastics have been identified in all living forms including human beings, the present need is to restrain its spread and devise measures to remediate microplastics from polluted ecosystems. In this regard, the present review emphasizes on the occurrence, sources detection and toxic effects of microplastics in various ecosystems. The removal of microplastics is prevalent by various physico-chemical and biological methods, although the removal efficiency by biological methods is low. It has been noted that the degradation of plastics by insect gut larvae is a well-known aspect, however, the underlying mechanism has not been completely identified. Studies conducted have shown the magnificent contribution of gut microbiota, which have been isolated and exploited for microplastic remediation. This review also focuses on this avenue, as it highlights the contribution of insect gut microbiota in microplastic degradation along with challenges faced and future prospects in this area.

Insights into the removal of microplastics and microfibres by Advanced Oxidation Processes

Water treatment plants' effluents are hotspots of microplastics (MPs) and microfibres (MFs) released into the aquatic environment because they were not designed to capture these particles. Special attention should be given to MFs, since they mainly come from laundry and are related to one of the main MP shapes detected in water and wastewater treatment plants. In this sense, Advanced Oxidation Processes (AOPs) could be a feasible solution for tackling MP and MF pollution, however, it is still premature to extract conclusions due to the limited number of studies on the degradation of these particles (specifically MFs) using AOPs. This review addresses the impacts of AOPs on MPs/MFs, focusing on their degradation efficiency, toxicity, and sustainability of the processes, among other aspects. The review points out that polyamide MFs can achieve mass loss >90% by photocatalytic system using TiO₂. Also, the low oxidation of MPs (<30 %) by conventional Fenton process affects mainly the surface of the MPs. However, other Fenton-based processes can provide better removal of some types of MPs, mainly using temperatures >100 °C, reaction time ≥ 5 h, and initial pH ≤ 3, achieving MP weight loss up to 96 %. Despite these results, better operating conditions are still required for AOPs since the ones reported so far are not feasible for full-scale application. Additionally, ozonation in treatment plants has increased the fragmentation of MPs (including MFs), leading to a new generation of MPs. More attention is needed on toxicity effects of intermediates and methods of analysis employed for the analysis of MPs/MFs in wastewater effluent should be standardized so that studies can be compared effectively. Future research should focus on the sustainability of the AOP for MP removal in water treatment (power consumption, chemicals consumed and operational costs) for a better understanding of full-scale applicability of AOP adapted to MP treatment.

Microplastics in Commercial Fishes and By-Catch from Selected FAO Major Fishing Areas of the Southern Baltic Sea

According to recent world wide studies, microplastics (MPs) have been found in many fish species; however, the majority of research has focused only on the gastrointestinal tract, neglecting edible organs. This study aimed to assess the presence of microplastics in the non-edible (gills, digestive tract) and edible organs (liver) of three commercial fish species and twoby-catch species from the southern Baltic Sea. Fish (Clupea harengus, Gadus morhua, Platichthy sflesus, Taurulus baublis, Cyclopterus lumpus) were caught in 108 and 103 FAO Fishing Zones belonging to the Polish fishing zone. The abundanceof MPs ranged from 1 to 12 items per fish, with an average of 4.09 items. MPs were observed in different organs, such as the liver, gills, and digestive tract of all five tested species. MPs recognized as fibers were the most abundant. Other shapes of polymers found in fish organs were pellets and particles of larger plastic pieces. The dominant color of the MPs was blue, but there were also red, black, transparent, yellow, green, and white items found. According to dimensions, dominant MPs were between 0.1 and 0.5 mm in size. The chemical characterization of polymers accomplished by the use of Fourier Transform Infrared (FT-IR) Spectroscopy demonstrated the abundance of cellophane, polyamide, polyethylene, polypropylene, polyethylene terephthalate, polyvinyl propionate, polyacrylonitrile, and polyester.

Spatiotemporal characterisation of microplastics in the coastal regions of Singapore

In the 21st century, plastic production continues to increase at an unprecedented rate, leading to the global issue of plastic pollution. In marine environments, a significant fraction of plastic litter are microplastics, which have a wide range of effects in marine ecosystems. Here, we examine the spatiotemporal distribution of microplastics along the Johor and Singapore Straits, at surface and at depth. Generally, more microplastics were recorded from the surface waters across both Straits. Fragments were the dominant microplastic type (70%), followed by film (25%) and fiber (5%). A total of seven colours of microplastics were identified, with clear microplastics as the most abundant (64.9%), followed by black (25.1%) and blue (5.5%). Microplastics under 500 μm in size accounted for 98.9%, followed by particles 500-1000 μm (1%) and 1-5 mm (0.1%). During the monsoon season, the abundance of microplastics across various sites were observed to be > 1.1 times when compared to the inter-monsoon period. Rainfall was a closely related to the increased microplastic abundance across various sites in the Singapore Strait. This suggests that weather variations during climate change can play critical roles in modulating microplastic availability. Beach sediments facing the Singapore Strait recorded an abundance of 13.1 particles/kg, with polypropylene fragments, polyethylene pellets and thermoplastic polyester foam identified via Fourier transform infrared spectroscopy. Hence, it is crucial to profile the spatiotemporal variation of microplastic abundance in both the surface and in the water column to gain a better understanding of the threat caused by microplastic pollution in the coastal regions of Singapore.

Plastic waste in sandy beaches and surface water in Thanh Hoa, Vietnam: abundance, characterization, and sources

The occurrence and characterization of marine debris on beaches bring opportunities to track back the anthropogenic activities around shorelines as well as aid in waste management and control. In this study, the three largest beaches in Thanh Hoa (Vietnam) were examined for plastic waste, including macroplastics (≥ 5 mm) on sandy beaches and microplastics (MPs) (< 5 mm) in surface water. Among 3803 items collected on the beaches, plastic waste accounted for more than 98%. The majority of the plastic wastes found on these beaches were derived from fishing boats and food preservation foam packaging. The FT-IR data indicated that the macroplastics comprised 77% polystyrene, 17% polypropylene, and 6% high-density polyethylene, while MPs discovered in surface water included other forms of plastics such as polyethylene- acrylate, styrene/butadiene rubber gasket, ethylene/propylene copolymer, and zein purified. FT-IR data demonstrated that MPs might also be originated from automobile tire wear, the air, and skincare products, besides being degraded from macroplastics. The highest abundance of MPs was 44.1 items/m³ at Hai Tien beach, while the lowest was 15.5 items/m³ at Sam Son beach. The results showed that fragment form was the most frequent MP shape, accounting for 61.4 ± 14.3% of total MPs. MPs with a diameter smaller than 500 μm accounted for 70.2 ± 7.6% of all MPs. According to our research, MPs were transformed, transported, and accumulated due to anthropogenic activities and environmental processes. This study provided a comprehensive knowledge of plastic waste, essential in devising long-term development strategies in these locations.

Assessing contamination of microplastics in the Ghanaian coastal sea using a self-constructed LADI trawl

Almost everywhere in the marine ecosystem contains microplastics. Although their environmental contamination is a global problem, relatively little is known about their distribution and abundance in the Gulf of Guinea. This study looked at the spatial dynamics of microplastics in the sea surface water off the coast of Ghana. Four chosen areas were found to have non-variable concentrations ranging from 1.14 to 2.79 particles m^-3 using a self-constructed Low-Tech Aquatic Debris Instrument (LADI) trawl (333 μm mesh). The most abundant shapes were fragments and pellets, while the most common colors were colored and transparent particles. The polymer types found in the microplastics selected for investigation using Fourier Transform Infrared spectroscopy in Attenuated Total Reflectance mode (ATR-FT-IR) were Polypropylene, Polyethylene, and Polystyrene. These results provide an important baseline on microplastic pollution along the Ghanaian coast suggesting the LADI trawl as an accurate quantitative sampling tool for microplastics from sea surface water.

Quantification and characterization of plastics in near-shore surface waters of Atlantic Canada

Plastics are a ubiquitous pollutant in the marine environment. Despite growing concerns, quantitative and qualitative data on microplastics in aquatic and marine environments of Atlantic Canada is just emerging. Surface water plastics were measured and categorized by morphology (thread, microfibre, fragment, foam, film, pellet, and microbead) in two locations in Nova Scotia and one in Newfoundland and Labrador, Canada. All sites within the three locations contained plastic with an average abundance of 9669 items/km². Most plastics (68 %) were sized as microplastics (0.425-5 mm), and plastic fragments were the most common morphological type. Polyethylene accounted for a third (30 %) of all particles found across all three locations, followed by polypropylene (23 %). Results can inform future research for community-based environmental groups, government, and academia.

Long-term interactions between microplastics and floating macrophyte Lemna minor: The potential for phytoremediation of microplastics in the aquatic environment

The presence of microplastics (MPs) in the environment has raised many concerns, and therefore approaches and technologies to remove them in situ are of high interest. In this context, we investigated the interactions between polyethylene MPs (fragments with a mean size of 149 ± 75 μm) and an aquatic floating macrophyte Lemna minor in order to assess its potential use for in situ phytoremediation. We first investigated the long-term effects of a high (100 mg/L = 9600 MPs/L), but still environmentally relevant concentration of MPs on L. minor. Subsequently bioadhesion of MPs was studied and the number and strength of MPs adhering to plant biomass were assessed. MPs did not adversely affect various parameters of plants (e.g., specific growth rate, chlorophyll contents, total antioxidant capacity, electron transport system activity, and contents of energy-rich molecules) throughout the duration of the experiment (12 weeks), except for the first week of the experiment, when protein content and total antioxidant capacity were affected. On the other hand, MPs affected the root length of L. minor during the first eight weeks of the experiment, while further exposure resulted in a decrease in the effects, indicating the ability of L. minor to tolerate the presence of MPs for a long period of time. MPs adhered rapidly to the plant biomass and the average percentages of strongly and weakly adhered particles were 6.5% and 20.0%, respectively, of the total MPs applied. In summary, results of this study suggest that L. minor can tolerate hotspot concentrations of MPs and can collect MPs from the water surface. Therefore, phytoremediation using floating plants could be considered as a potential method for in situ removal of MPs from the aquatic environment.

Review on Monitoring, Operation and Maintenance of Smart Offshore Wind Farms

In recent years, with the development of wind energy, the number and scale of wind farms have been developing rapidly. Since offshore wind farms have the advantages of stable wind speed, being clean, renewable, non-polluting, and the non-occupation of cultivated land, they have gradually become a new trend in the wind power industry all over the world. The operation and maintenance of offshore wind power has been developing in the direction of digitization and intelligence. It is of great significance to carry out research on the monitoring, operation, and maintenance of offshore wind farms, which will be of benefit for the reduction of the operation and maintenance costs, the improvement of the power generation efficiency, improvement of the stability of offshore wind farm systems, and the building of smart offshore wind farms. This paper will mainly summarize the monitoring, operation, and maintenance of offshore wind farms, with particular focus on the following points: monitoring of “offshore wind power engineering and biological and environment”, the monitoring of power equipment, and the operation and maintenance of smart offshore wind farms. Finally, the future research challenges in relation to the monitoring, operation, and maintenance of smart offshore wind farms are proposed, and the future research directions in this field are explored, especially in marine environment monitoring, weather and climate prediction, intelligent monitoring of power equipment, and digital platforms.

Seeking for a perfect (non-spherical) microplastic particle - The most comprehensive review on microplastic laboratory research

In recent decades, much attention has been paid to microplastic pollution, and research on microplastics has begun to grow exponentially. However, microplastics research still suffers from the lack of standardized protocols and methods for investigation of microplastics under laboratory conditions. Therefore, in this review, we summarize and critically discuss the results of 715 laboratory studies published on microplastics in the last five years to provide recommendations for future laboratory research. Analysis of the data revealed that the majority of microplastic particles used in laboratory studies are manufactured spheres of polystyrene ranging in size from 1 to 50 µm, that half of the studies did not characterize the particles used, and that a minority of studies used aged particles, investigated leaching of chemicals from microplastics, or used natural particles as a control. There is a large discrepancy between microplastics used in laboratory research and those found in the environment, and many laboratory studies suffer from a lack of environmental relevance and provide incomplete information on the microplastics used. We have summarized and discussed these issues and provided recommendations for future laboratory research on microplastics focusing on (i) microplastic selection, (ii) microplastic characterization, and (iii) test design of laboratory research on microplastics.

Effects of polystyrene microplastic on the growth and volatile halocarbons release of microalgae Phaeodactylum tricornutum

Volatile halocarbons (VHCs) are trace greenhouse gases that can damage the ozone layer. Trihalomethanes are one of the most common VHCs and play an important role in global climate change. Due to their steadily increasing abundance, microplastics pollutants have attracted growing concern from scientists. However, their impacts on the growth of marine microalgae and the release of VHCs remain unknown. The influence of polystyrene microplastic (PS, 0.1 μm) at different concentrations (25-200 mg/L) on the growth of P. tricornutum and their release of trihalomethanes were studied over 96 h. The results showed that PS can inhibit P. tricornutum growth. At 200 mg/L PS, cell growth, chlorophyll a concentration and photosynthetic efficiency of P. tricornutum were inhibited by 53.53%, 25.45% and 12.50%, respectively. PS concentrations of 25-50 mg/L promoted the release of the three trihalomethanes by P. tricornutum during the 96 h culture as a response to oxidative stress. However, 100-200 mg/L PS severely altered the physiological state of the P. tricornutum cells after 48 h, which reduced the release of trihalomethanes. Our study also demonstrated that the production and release of trihalomethanes served as a protective mechanism against oxidative stress and the toxic effects caused by PS.

Are we contaminating our samples? A preliminary study to investigate procedural contamination during field sampling and processing for microplastic and anthropogenic microparticles

Methods for sampling, analysis and interpretation of fresh and saltwater microplastics and anthropogenic microfibers have improved since 2004, but techniques for reducing and monitoring procedural contamination are still limited. Quantifying the amount of procedural contamination introduced to samples improves the robustness of counts of microplastics and anthropogenic microfibers in the environment. This pilot study investigates procedural contamination introduced into water samples when rigorous QA/QC anti-contamination protocols are used and removed. Procedural contamination accounted for 33.8% of the total microfibers and microplastics found in samples when protocols were used (n = 81), but 70.7% when they were not (n = 8). With the use of extensive control sampling and full characterization of samples (morphological, optical and chemical) it was possible to identify the predominant sources of contamination (crew clothing) and make recommendations for anti-contamination and procedural contamination identification/reduction protocols for shoreline and small/medium sized vessel sampling for microplastics and anthropogenic microfibers.

Effects of polystyrene and triphenyl phosphate on growth, photosynthesis and oxidative stress of Chaetoceros meülleri

The toxicity of microplastics to marine organisms has attracted much attention; however, studies of their effects on marine microalgae remain limited. Here, the effects of the single and combined toxicity of polystyrene (PS) and triphenyl phosphate (TPhP) on the cell growth, photosynthesis, and oxidative stress of Chaetoceros meülleri were investigated. PS inhibited growth of the algae cells and caused a dose-dependent effect on oxidative stress. The significantly high production of reactive oxygen species (ROS) induced severe cell membrane damage, as confirmed by high fluorescence polarization. However, there was no obvious decrease in chlorophyll a content, and 80 mg/L of PS significantly promoted chlorophyll a synthesis. The TPhP also inhibited cell growth, except at low concentrations (0.2-0.8 mg/L), which stimulated algae growth over 48 h. Moreover, no obvious decrease in chlorophyll a and maximal photochemical efficiency of PSII was found in the TPhP experimental groups except for 3.2 mg/L TPhP, where the rapid light curves showed a significantly reduced photosynthetic capacity of algae. In addition, TPhP caused high ROS levels at 96 h, resulting in cell membrane damage. Using the additive index and independent action methods, the combined toxic effects of PS and TPhP on the algae were evaluated as antagonistic; however, cell membrane damage caused by high ROS levels was still noticeable. This study has shown the potential toxicity of PS and TPhP to marine microalgae, and provided insights into the combined risk assessment of TPhP and microplastics in the marine environment.

Occurrence and spatial distribution of microplastics in the surface waters of the Baltic Sea and the Gulf of Riga

The study is comparing microplastic debris distribution and composition in the Gulf of Riga and the Eastern Gotland Basin, Baltic Sea. Samples from 44 stations were collected from coastal and open water sites using Manta trawl (mesh size 300 μm). The natural organic material was digested sequentially with sodium hydroxide, hydrogen peroxide and enzymes. Thereafter, micro-debris (16,315 particles) was identified by visual analysis and 5285 particles were analyzed with Attenuated Total Reflection Fourier Transform Infrared spectroscopy method. The abundance of particles varied from 0.09 to 4.43 particles per m-3. The fibers accounted for 66.1% of all encountered particles while the fragments for 30.2%. The predominant polymer types were polyethylene (77.9%) and polypropylene (11.1%). The relative proportion among polymer types varied considerably from station to station. The encountered concentrations of micro-debris were well in range of values reported from other regions of the Baltic Sea.

A proposed nomenclature for microplastic contaminants

Microplastics are emerging contaminants with a wide environmental distribution and potential to elicit adverse impacts on organisms. Despite this lack of consistency among reports, data obtained from different investigations are often compared, resulting in the potential for misrepresentation of global microplastic contamination. Major interlaboratory variability in quantification of microplastic levels stem from size-related differences in sampling and analysis with different density solutions to separate microplastics. Herein, we propose a nomenclature that provides key information relating to the microplastics abundance in samples. That is, the proposed nomenclature, MPs_c^{a, b}, informs on mesh or filter size used in sampling, the density of flotation solution used to separate the microplastics, and the detection limit during the analysis progress of microplastics. This proposed nomenclature would facilitate comparisons among studies to avoid over- or under-estimation of global microplastic levels. Moreover, it would also facilitate the interpretation of meta-data in future assessments.

Review of Microplastic Distribution, Toxicity, Analysis Methods, and Removal Technologies

Microplastic contamination has become a problem, as plastic production has increased worldwide. Microplastics are plastics with particles of less than 5 mm and are absorbed through soil, water, atmosphere, and living organisms and finally affect human health. However, information on the distribution, toxicity, analytical methods, and removal techniques for microplastics is insufficient. For clear microplastic analytical methods and removal technologies, this article includes the following: (1) The distribution and contamination pathways of microplastics worldwide are reviewed. (2) The health effects and toxicity of microplastics were researched. (3) The sampling, pretreatment, and analytical methods of microplastics were all reviewed through various related articles. (4) The various removal techniques of microplastics were categorized by wastewater treatment process, physical treatment, chemical treatment, and biological treatment. This paper will be of great help to microplastic analysis and removal techniques.

Disparities in Methods Used to Determine Microplastics in the Aquatic Environment: A Review of Legislation, Sampling Process and Instrumental Analysis

Plastic particles smaller than 5 mm, i.e., microplastics, have been detected in a number of environments. The number of studies on microplastics in marine environments, fresh water, wastewater, the atmosphere, and the human body are increasing along with a rise in the amounts of plastic materials introduced into the environment every year, all contributing to a range of health and environmental issues. Although the use of primary microplastics has been gradually reduced by recent legislation in many countries, new knowledge and data on these problems are needed to understand the overall lifecycle of secondary microplastics in particular. The aim of this review is to provide unified information on the pathways of microplastics into the environment, their degradation, and related legislation, with a special focus on the methods of their sampling, determination, and instrumental analysis. To deal with the health and environmental issues associated with the abundance of microplastics in the environment, researchers should focus on agreeing on a uniform methodology to determine the gravity of the problem through obtaining comparable data, thus leading to new and stricter legislation enforcing more sustainable plastic production and recycling, and hopefully contributing to reversing the trend of high amounts of microplastics worldwide.